Integrated circuit fabrication may involve formation of a lightly-doped semiconductor material over a heavily-doped semiconductor material, followed by out-diffusion of dopant from the heavily-doped semiconductor material into the lightly-doped semiconductor material. Difficulties may be encountered if the heavily-doped semiconductor material is exposed to oxidative conditions prior to formation of the lightly-doped semiconductor material. For instance, dopant of the heavily-doped semiconductor material may oxidize to reduce an effective concentration of dopant and/or to form a barrier which impedes out-diffusion. Additionally, or alternatively, the semiconductor material may oxidize to form a barrier which impedes out-diffusion.
It would be desirable to develop new methods and structures which alleviate or prevent the above-discussed difficulties.